5 INSTALLED SYSTEMS
5.3 Conformance .1 USER POSTURES
when the user contacts a conductive surface. Potentials on either the screen or the user can be discharged very quickly (e.g., 50 ms) to produce a shock. Shocks can be uncomfortable and annoying and can cause unplanned movement of a limb. The energy from these shocks is limited (less than 100 millijoules), so it is not dangerous to the user.
5.3 Conformance
Measure and record the angle. Verify that the angle is 10 degrees or less if the wrist is extended (bent up) or that the angle is 30 degrees or less if the wrist is flexed (bent down).
Torso-thigh angle measurement. To measure the torso-to-thigh angle, use a manual goniometer.
Place the axis of the goniometer over the greater trochanter (bony prominence in the hip joint).
Place one arm of the goniometer protractor along an imaginary line running up through the center of the user’s torso and the second arm along the midline of the femur (upper leg) pointing toward the knee. Measure and record the angle. Verify that the angle is at least 90 degrees.
5.3.2 CONTROL CLEARANCE FOR USER’S FEET AND LEGS
Verify compliance with the leg and foot clearance specifications in Chapter 8. Furniture, Section 8.3.2.1, Operator Clearances.
Observe whether controls, when not in use, inadvertently come into contact with the legs and/or feet.
Verify that the controls are in the intended nonuse position.
Observe if controls interfere with the user’s ability to perform work activities when the controls are not in use.
5.3.3 PINCH POINTS
Verify that pinch points allow sufficient clearance to avoid pinching the body part likely to be entrapped.
5.3.4 LEG AND FOOT CLEARANCE
The installed system, including the chair, shall
• Verify compliance with furniture chapter specifications for leg and foot clearance requirements
• Verify that workstation allows the user to sit in reference postures without any portion of the workstation touching the user’s legs and/or feet while he/she is in the selected reference posture or postures
5.3.5 FOOTRESTS
Verify by observation that user’s feet are supported on floor or footrest when they are in the selected seated postures and in conformance with 5.2.1.1.
5.3.6 CHAIRS
Verify lumbar support, reclining backrest, seat pan adjustability, and ability to meet two of the three seated reference posture criteria by observation or manufacturer’s specifications.
Verify that the chair is correctly adjusted for appropriate leg and foot clearance by applying the criteria from 5.2.1.1.
Verify by observation that the chair supports the user’s torso and thighs. Note: The chair’s lumbar support should provide support to the low back (lumbar region clearance between the back of the user’s legs and the front edge of the chair).
5.3.7 CHAIR SEAT PAN AND BACKREST ADJUSTMENTS
Verify by observation that the backrest and/or seat pan are not adjusted in a manner that positions the user’s torso forward of vertical.
Verify that the backrest and/or seat pan of the chair are not adjusted in a manner that forces a torso- thigh angle less than 90 degrees.
Verify by observation or by manufacturer’s claim that the angle between the seat pan and backrest can be adjusted to an angle of 90 degrees or more.
Verify by observation or by manufacturer’s claim that the chair backrest allows the user to recline at least 15 degrees behind vertical.
5.3.8 ARMRESTS
Verify sufficient clearance between the armrests by observation. Determine whether the user can sit in, or arise from, the chair without the user’s hips, buttocks, or thighs touching the armrests. This prohibition against touching the armrests specifically does not include grasping the armrests to assist movement.
Verify that utilizing the armrests of the chair does not cause the user to assume postures that are contrary to the requirements of User Postures specifications. Observe and/or measure the postural angles as described in Section 5.2.1.1 while the user is seated in the chair and using the armrests to support his/her arms.
5.3.9 INPUT DEVICE LOCATION
The recommended space for placement of input devices is directly in front of the user. To determine the recommended space for placement of the input device or devices for any individual user:
1. Determine whether the user’s selected working posture conforms to the requirements of Section 5.2.1.1. Particular attention should be given to shoulder abduction, elbow angle, and forearm/wrist angle.
2. Determine the user’s shoulder breadth. This may be measured as the distance between the acromial processes or approximated by observation. The distance between the user’s shoulders is the width of the recommended space.
3. Determine the length of the user’s forearm. This may be measured as the distance from the oleacronon (tip of the elbow) to the tip of the index finger. The recommended space is as deep as the length of the user’s forearm.
If the input device(s) is placed within the space delimited by the user’s forearm length and shoulder breadth and if the user’s working posture conforms with Section 5.2.1.1, the input device(s) is appropriately located with regard to height and tilt.
Evaluation of leg and foot clearances for the input device may be assessed as in conformance Section 5.2.2.1.
Verify that the workstation is adjusted so that the user meets the postural criteria of Section 5.2.1.1 for the selected working postures. Note that conformance requires meeting the criteria.
Verify that the range of adjustment for height and tilt is available.
Verify by observation or from the manufacturer claims that the workstation can be used in at least one of the seated reference postures as well as in the standing posture while maintaining conformance with Section 5.2.1.1.
5.3.10 MONITOR SUPPORT SURFACE
Verify that the user can adjust the viewing distance of the monitor by moving it closer to, or away from, the eyes.
Verify that the user can tilt and rotate the display.
5.3.11 ILLUMINANCE
The system integrator will generally verify this provision by the absence of noticeable or distracting reflections on the computer screen.